As for why we lose people in swaps, life happens. It's been my experience with this swap that sometimes life has gotten in the way. What I really don't like, though, is when people don't communicate. I'd MUCH rather see "Hey, life's getting in the way; I can't meet my commitment" than to see thin air.
AND having said all that, I am AMAZED that despite what life has thrown several participants in this swap, including bypass surgery and family emergencies, they STILL managed to finish a quilt for a stranger.